Hereditary ataxias are a group of diseases which include spinocerebellar degenerations and olivopontocerebellar atrophies. The Schut-Swier kindred has an autosomal dominant form of spinocerebellar ataxia (SCA) genetically linked to the HLA complex chromosome 6. DNA markers will be isolated from chromosome 6 which permit the delection of polymorphic restriction endonuclease sites in the Schut-Swier kindred. These markers will be mapped to sub-regions along chromosome 6. A panel of mapped markers will then be used to probe genomic DNA from lymphoblastoid cell lines established from 80 members of the Schut-Swier kindred. These data will be analyzed for restriction fragments linked to the SCA gene. The establishment of a linked marker(s) to SCA will permit: 1) The identification of individuals carrying the SCA gene within the Schut-Swier kindred. This information will enable more precise genetic counseling. Members of this kindred have proven to be very responsive to past counseling by Dr. Schut. 2) Determining if SCA in other kindreds is due to a mutation in the same locus as the Schut-Swier kindred, 3) The use of molecular biological methods to isolate and characterize the SCA gene.